package com.woniuxy.shiro.utils;

import org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @author: mayuhang  <br/>
 * Date: 2021/4/23:0:24  <br/>
 * Description:继承官方的BasicHttpAuthenticationFilter，并且重写鉴权的方法
 * 代码的执行流程preHandle->isAccessAllowed->isLoginAttempt->executeLogin
 */
@Component
public class JWTFilter extends BasicHttpAuthenticationFilter {
    /**
     * 对跨域提供支持
     */
    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
        // 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            httpServletResponse.setStatus(HttpStatus.OK.value());
            return false;
        }
        return super.preHandle(request, response);
    }
    /**
     * 这里我们详细说明下为什么最终返回的都是true，即允许访问
     * 例如我们提供一个地址 GET /article
     * 登入用户和游客看到的内容是不同的
     * 如果在这里返回了false，请求会被直接拦截，用户看不到任何东西
     * 所以我们在这里返回true，Controller中可以通过 subject.isAuthenticated() 来判断用户是否登入
     * 如果有些资源只有登入用户才能访问，我们只需要在方法上面加上 @RequiresAuthentication 注解即可
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        if (isLoginAttempt(request, response)) {
            try {
                //如果有token
                executeLogin(request, response);
            } catch (Exception e) {
                //如果请求头没有带Authorization属性的token 就到这里咯
                response401(request, response);
            }
        }
        return true;
    }
    /**
     * 判断用户是否想要登入。
     * 检测header里面是否包含Authorization字段即可
     */
    @Override
    protected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {
        HttpServletRequest hsr = (HttpServletRequest) request;
        String authorization = hsr.getHeader("Authorization");
        return authorization!=null;
    }

    @Override
    protected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        //从请求头中获取token
        String authorization = httpServletRequest.getHeader("Authorization");
        //放入对象中, redis或者数据库查询  等同于之前的UsernamePasswordToken
        MyJsonWebToken token = new MyJsonWebToken(authorization);
        // 提交给realm进行登入，如果错误他会抛出异常并被捕获
        System.out.println("JWTFilter.executeLogintoken交给realm判断:"+token);
        //这个等同于直接的 subject.login(token)
        getSubject(request, response).login(token);
        // 如果没有抛出异常则代表登入成功，返回true
        return true;
    }
        /**
         * 将非法请求跳转到 /401
         */
    private void response401(ServletRequest req, ServletResponse resp) {
        try {
            HttpServletResponse httpServletResponse = (HttpServletResponse) resp;
            httpServletResponse.sendRedirect("/401");
        } catch (IOException e) {
            System.err.println(e.getMessage());
        }
    }
}
